1. Field of the Invention
The invention relates to a process for forming a silicon carbide structure.
2. Background Art
Silicon carbide is useful in many applications because of its excellent high temperature strength, chemical durability, high oxidation resistance, high abrasion resistance, and high thermal conductivity. In the automotive industry, for example, silicon carbide structures are used to filter particulate material from exhaust gases of diesel engines. Typically, the geometry of the silicon carbide filter is honeycomb. The honeycomb geometry provides a very high surface area per unit volume, allowing a large amount of particulate material to be packed into the filter body.
Current methods for producing silicon carbide structures generally include sintering a green body of particulate material at very high temperatures, typically in excess of 2000xc2x0 C., for many hours. This makes silicon carbide structures very expensive to produce. Therefore, a method of producing silicon carbide structures at lower temperatures would be beneficial.
In one aspect, the invention relates to a process for forming a silicon carbide structure which comprises molding by compression a mixture of a silicon precursor powder and a cross-linking thermoset resin to form a rigid structure, carbonizing the rigid structure, and forming a silicon carbide structure by heating the carbonized rigid structure at a temperature sufficient to allow carbon and silicon in the structure to react to form silicon carbide.
In another aspect, the invention relates to a process for forming a silicon carbide structure which comprises compression-molding a mixture of a silicon precursor powder, a cross-linking thermoset resin, and a silicon carbide powder to form a rigid structure, carbonizing the rigid structure, and forming a silicon carbide structure by heating the carbonized rigid structure at a temperature sufficient to allow carbon and silicon in the structure to react to form silicon carbide.
In another aspect, the invention relates to a process for forming a silicon carbide structure which comprises compression-molding a mixture of a silicon precursor powder and a cross-linking thermoset resin to form a rigid structure, carbonizing the rigid structure in an inert atmosphere at a temperature in a range from about 700 to 1000xc2x0 C. to convert the cross-linking thermoset resin to carbon, and heating the rigid structure in an inert atmosphere to a temperature in a range from about 1400 to 1800xc2x0 C. to allow the carbon to react with silicon in the rigid structure to form silicon carbide.
Other features and advantages of the invention will be apparent from the following description and the appended claims.